target: add generic Xtensa LX support

Generic Xtensa LX support extends the original Espressif/Xtensa
patch-set to support arbitrary Xtensa configurations, as defined in
a core-specific .cfg file.  Not yet fully-featured.  Additional
functionality to be added:
- Xtensa NX support
- DAP/SWD support
- File-IO support
- Generic Xtensa multi-core support

Valgrind-clean, no new Clang analyzer warnings

Signed-off-by: Ian Thompson <ianst@cadence.com>
Change-Id: I08e7bf8fa57c25b5d0cb75a1aa7a2ac13a380c52
Reviewed-on: https://review.openocd.org/c/openocd/+/7055
Tested-by: jenkins
Reviewed-by: Erhan Kurubas <erhan.kurubas@espressif.com>
Reviewed-by: Antonio Borneo <borneo.antonio@gmail.com>

src/target/xtensa/xtensa_chip.h

@@ -0,0 +1,34 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+/***************************************************************************
+ *   Xtensa Chip-level Target Support for OpenOCD                          *
+ *   Copyright (C) 2020-2022 Cadence Design Systems, Inc.                  *
+ ***************************************************************************/
+
+#ifndef OPENOCD_TARGET_XTENSA_CHIP_H
+#define OPENOCD_TARGET_XTENSA_CHIP_H
+
+#include <target/target.h>
+#include "xtensa.h"
+#include "xtensa_debug_module.h"
+
+struct xtensa_chip_common {
+	struct xtensa xtensa;
+	/* Chip-specific extensions can be added here */
+};
+
+static inline struct xtensa_chip_common *target_to_xtensa_chip(struct target *target)
+{
+	return container_of(target->arch_info, struct xtensa_chip_common, xtensa);
+}
+
+int xtensa_chip_init_arch_info(struct target *target, void *arch_info,
+	struct xtensa_debug_module_config *dm_cfg);
+int xtensa_chip_target_init(struct command_context *cmd_ctx, struct target *target);
+int xtensa_chip_arch_state(struct target *target);
+void xtensa_chip_queue_tdi_idle(struct target *target);
+void xtensa_chip_on_reset(struct target *target);
+bool xtensa_chip_on_halt(struct target *target);
+void xtensa_chip_on_poll(struct target *target);
+
+#endif	/* OPENOCD_TARGET_XTENSA_CHIP_H */